From: Minchan Kim <minchan@kernel.org>
To: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Joonsoo Kim <js1304@gmail.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH v2 3/3] mm/zsmalloc: increase ZS_MAX_PAGES_PER_ZSPAGE
Date: Mon, 22 Feb 2016 10:34:42 +0900 [thread overview]
Message-ID: <20160222013442.GB27829@bbox> (raw)
In-Reply-To: <20160222004758.GB4958@swordfish>
On Mon, Feb 22, 2016 at 09:47:58AM +0900, Sergey Senozhatsky wrote:
> On (02/22/16 09:25), Minchan Kim wrote:
> [..]
> > I tempted it several times with same reason you pointed out.
> > But my worry was that if we increase ZS_MAX_ZSPAGE_ORDER, zram can
> > consume more memory because we need several pages chain to populate
> > just a object. Even, at that time, we didn't have compaction scheme
> > so fragmentation of object in zspage is huge pain to waste memory.
>
> well, the thing is -- we end up requesting less pages after all, so
> zsmalloc has better chances to survive. for example, gcc5 compilation test
Indeed. I saw your test result.
>
> BASE
>
> 168 2720 0 1 115833 115831 77222 2
> 190 3072 0 1 109708 109707 82281 3
> 202 3264 0 5 1910 1895 1528 4
> 254 4096 0 0 380174 380174 380174 1
>
> Total 44 285 1621495 1618234 891703
>
>
> PATCHED
>
> 192 3104 1 0 3740 3737 2860 13
> 194 3136 0 1 7215 7208 5550 10
> 197 3184 1 0 11151 11150 8673 7
> 199 3216 0 1 9310 9304 7315 11
> 200 3232 0 1 4731 4717 3735 15
> 202 3264 0 1 8400 8396 6720 4
> 206 3328 0 1 22064 22051 17927 13
> 207 3344 0 1 4884 4877 3996 9
> 208 3360 0 1 4420 4415 3640 14
> 211 3408 0 1 11250 11246 9375 5
> 212 3424 1 0 3344 3343 2816 16
> 214 3456 0 2 7345 7329 6215 11
> 217 3504 0 1 10801 10797 9258 6
> 219 3536 0 1 5295 5289 4589 13
> 222 3584 0 0 6008 6008 5257 7
> 223 3600 0 1 1530 1518 1350 15
> 225 3632 0 1 3519 3514 3128 8
> 228 3680 0 1 3990 3985 3591 9
> 230 3712 0 2 2167 2151 1970 10
> 232 3744 1 2 1848 1835 1694 11
> 234 3776 0 2 1404 1384 1296 12
> 235 3792 0 2 672 654 624 13
> 236 3808 1 2 615 592 574 14
> 238 3840 1 2 1120 1098 1050 15
> 254 4096 0 0 241824 241824 241824 1
>
> Total 129 489 1627756 1618193 850147
>
>
> that's 891703 - 850147 = 41556 less pages. or 162MB less memory used.
> 41556 less pages means that zsmalloc had 41556 less chances to fail.
Let's think swap-case which is more important for zram now. As you know,
most of usecase are swap in embedded world.
Do we really need 16 pages allocator for just less PAGE_SIZE objet
at the moment which is really heavy memory pressure?
>
>
> > Now, we have compaction facility so fragment of object might not
> > be a severe problem but still painful to allocate 16 pages to store
> > 3408 byte. So, if we want to increase ZS_MAX_ZSPAGE_ORDER,
> > first of all, we should prepare dynamic creating of sub-page of
> > zspage, I think and more smart compaction to minimize wasted memory.
>
> well, I agree, but given that we allocate less pages, do we really want to
> introduce this complexity at this point?
I agree with you. Before dynamic subpage chaining feature, we need
lots of testing in heavy memory pressure with zram-swap.
However, I think the feature itself is good to have in the future. :)
>
> -ss
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
WARNING: multiple messages have this Message-ID (diff)
From: Minchan Kim <minchan@kernel.org>
To: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
Joonsoo Kim <js1304@gmail.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC][PATCH v2 3/3] mm/zsmalloc: increase ZS_MAX_PAGES_PER_ZSPAGE
Date: Mon, 22 Feb 2016 10:34:42 +0900 [thread overview]
Message-ID: <20160222013442.GB27829@bbox> (raw)
In-Reply-To: <20160222004758.GB4958@swordfish>
On Mon, Feb 22, 2016 at 09:47:58AM +0900, Sergey Senozhatsky wrote:
> On (02/22/16 09:25), Minchan Kim wrote:
> [..]
> > I tempted it several times with same reason you pointed out.
> > But my worry was that if we increase ZS_MAX_ZSPAGE_ORDER, zram can
> > consume more memory because we need several pages chain to populate
> > just a object. Even, at that time, we didn't have compaction scheme
> > so fragmentation of object in zspage is huge pain to waste memory.
>
> well, the thing is -- we end up requesting less pages after all, so
> zsmalloc has better chances to survive. for example, gcc5 compilation test
Indeed. I saw your test result.
>
> BASE
>
> 168 2720 0 1 115833 115831 77222 2
> 190 3072 0 1 109708 109707 82281 3
> 202 3264 0 5 1910 1895 1528 4
> 254 4096 0 0 380174 380174 380174 1
>
> Total 44 285 1621495 1618234 891703
>
>
> PATCHED
>
> 192 3104 1 0 3740 3737 2860 13
> 194 3136 0 1 7215 7208 5550 10
> 197 3184 1 0 11151 11150 8673 7
> 199 3216 0 1 9310 9304 7315 11
> 200 3232 0 1 4731 4717 3735 15
> 202 3264 0 1 8400 8396 6720 4
> 206 3328 0 1 22064 22051 17927 13
> 207 3344 0 1 4884 4877 3996 9
> 208 3360 0 1 4420 4415 3640 14
> 211 3408 0 1 11250 11246 9375 5
> 212 3424 1 0 3344 3343 2816 16
> 214 3456 0 2 7345 7329 6215 11
> 217 3504 0 1 10801 10797 9258 6
> 219 3536 0 1 5295 5289 4589 13
> 222 3584 0 0 6008 6008 5257 7
> 223 3600 0 1 1530 1518 1350 15
> 225 3632 0 1 3519 3514 3128 8
> 228 3680 0 1 3990 3985 3591 9
> 230 3712 0 2 2167 2151 1970 10
> 232 3744 1 2 1848 1835 1694 11
> 234 3776 0 2 1404 1384 1296 12
> 235 3792 0 2 672 654 624 13
> 236 3808 1 2 615 592 574 14
> 238 3840 1 2 1120 1098 1050 15
> 254 4096 0 0 241824 241824 241824 1
>
> Total 129 489 1627756 1618193 850147
>
>
> that's 891703 - 850147 = 41556 less pages. or 162MB less memory used.
> 41556 less pages means that zsmalloc had 41556 less chances to fail.
Let's think swap-case which is more important for zram now. As you know,
most of usecase are swap in embedded world.
Do we really need 16 pages allocator for just less PAGE_SIZE objet
at the moment which is really heavy memory pressure?
>
>
> > Now, we have compaction facility so fragment of object might not
> > be a severe problem but still painful to allocate 16 pages to store
> > 3408 byte. So, if we want to increase ZS_MAX_ZSPAGE_ORDER,
> > first of all, we should prepare dynamic creating of sub-page of
> > zspage, I think and more smart compaction to minimize wasted memory.
>
> well, I agree, but given that we allocate less pages, do we really want to
> introduce this complexity at this point?
I agree with you. Before dynamic subpage chaining feature, we need
lots of testing in heavy memory pressure with zram-swap.
However, I think the feature itself is good to have in the future. :)
>
> -ss
next prev parent reply other threads:[~2016-02-22 1:34 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-21 13:27 [RFC][PATCH v2 0/3] mm/zsmalloc: increase objects density and reduce memory wastage Sergey Senozhatsky
2016-02-21 13:27 ` Sergey Senozhatsky
2016-02-21 13:27 ` [RFC][PATCH v2 1/3] mm/zsmalloc: introduce zs_get_huge_class_size_watermark() Sergey Senozhatsky
2016-02-21 13:27 ` Sergey Senozhatsky
2016-02-21 13:27 ` [RFC][PATCH v2 2/3] zram: use zs_get_huge_class_size_watermark() Sergey Senozhatsky
2016-02-21 13:27 ` Sergey Senozhatsky
2016-02-22 0:04 ` Minchan Kim
2016-02-22 0:04 ` Minchan Kim
2016-02-22 0:40 ` Sergey Senozhatsky
2016-02-22 0:40 ` Sergey Senozhatsky
2016-02-22 1:27 ` Minchan Kim
2016-02-22 1:27 ` Minchan Kim
2016-02-22 1:59 ` Sergey Senozhatsky
2016-02-22 1:59 ` Sergey Senozhatsky
2016-02-22 2:05 ` Sergey Senozhatsky
2016-02-22 2:05 ` Sergey Senozhatsky
2016-02-22 2:57 ` Minchan Kim
2016-02-22 2:57 ` Minchan Kim
2016-02-22 3:54 ` Sergey Senozhatsky
2016-02-22 3:54 ` Sergey Senozhatsky
2016-02-22 4:54 ` Minchan Kim
2016-02-22 4:54 ` Minchan Kim
2016-02-22 5:05 ` Sergey Senozhatsky
2016-02-22 5:05 ` Sergey Senozhatsky
2016-02-21 13:27 ` [RFC][PATCH v2 3/3] mm/zsmalloc: increase ZS_MAX_PAGES_PER_ZSPAGE Sergey Senozhatsky
2016-02-21 13:27 ` Sergey Senozhatsky
2016-02-22 0:25 ` Minchan Kim
2016-02-22 0:25 ` Minchan Kim
2016-02-22 0:47 ` Sergey Senozhatsky
2016-02-22 0:47 ` Sergey Senozhatsky
2016-02-22 1:34 ` Minchan Kim [this message]
2016-02-22 1:34 ` Minchan Kim
2016-02-22 2:01 ` Sergey Senozhatsky
2016-02-22 2:01 ` Sergey Senozhatsky
2016-02-22 2:34 ` Minchan Kim
2016-02-22 2:34 ` Minchan Kim
2016-02-22 3:59 ` Sergey Senozhatsky
2016-02-22 3:59 ` Sergey Senozhatsky
2016-02-22 4:41 ` Minchan Kim
2016-02-22 4:41 ` Minchan Kim
2016-02-22 10:43 ` Sergey Senozhatsky
2016-02-22 10:43 ` Sergey Senozhatsky
2016-02-23 8:25 ` Minchan Kim
2016-02-23 8:25 ` Minchan Kim
2016-02-23 10:35 ` Sergey Senozhatsky
2016-02-23 10:35 ` Sergey Senozhatsky
2016-02-23 16:05 ` Minchan Kim
2016-02-23 16:05 ` Minchan Kim
2016-02-27 6:31 ` Sergey Senozhatsky
2016-02-27 6:31 ` Sergey Senozhatsky
2016-02-22 2:24 ` Sergey Senozhatsky
2016-02-22 2:24 ` Sergey Senozhatsky
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20160222013442.GB27829@bbox \
--to=minchan@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=js1304@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=sergey.senozhatsky.work@gmail.com \
--cc=sergey.senozhatsky@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.